1. Technical Field of the Invention
The present invention generally relates to a device for making pellets. More specifically, the invention relates to the making of pellets of materials which have to be cooled or heated in order to obtain the solid form, i.e. whose temperature has to be changed. The invention also relates to a conveyor belt that is useful in such a device.
2. Prior Art
It is already known to make frozen pellets by freezing a liquid mass on a belt, or between two belts, that are sufficiently cooled for the mass to solidify to a carpet. Then the solidified carpet is divided into smaller pieces or pellets by breaking or sawing.
The resulting pieces may easily become different in size, and their shape often differs from the desired one. Moreover, considerable quantities of waste are produced, which at the best may be reused in the process.
Another difficulty in making pellets by cooling or heating on a belt is the tendency of many materials to adhere to the belt. Forming pellets by means of separate indentations in the belt thus usually leads to problems in the removal of the formed pellets from the indentations.
An object of the present invention is thus to provide a device and a conveyor belt which substantially eliminate the problems of prior art regarding waste and adherence.
The invention thus relates to a device for making pellets of a material that can be made to solidify by changing its temperature. The device comprises an endless belt on which the material is placed at a feeding location and is conveyed along a processing path to a guide roller at a discharging location. Furthermore, the device comprises means for changing the temperature of the material on the belt along the processing path. According to the invention, the endless belt comprises a plurality of transverse lamellae, which are articulately juxtaposed and have at least one duct which is extended in the longitudinal direction of the belt and has, between the edges of each lamella against adjacent lamellae, a transverse ridge of a height smaller than the depth of the duct.
As a consequence of the above-described construction, the material, which is supplied to the duct and essentially fills it, forms a continuous rib, which as the conveyor belt reaches the guide roller has solidified at least over its surface contacting the conveyor belt, but alternatively over its whole circumferential surface also comprising the free surface of the rib. As the belt moves round the guide roller, the lamellae will gradually be detached from the rib. As a result of the position of the ridges on the inside of the respective lamellae, each portion of the rib between two adjacent ridges will be separated from the conveyor belt in two steps, which facilitates the detachment. The ridges form excellent fracture lines in the rib in such a manner that when being detached from the conveyor belt, the rib is easily broken into pellets of a length corresponding to the distance between two adjacent ridges, or at least may very easily be made to be broken into such pellets as it being detached from the belt.
In order to obtain a desirable capacity of the device, the endless belt preferably has a plurality of separate ducts, which conveniently are parallel. More particularly, the ducts should be designed in such a manner that the rib formed in each duct does not engage the rib in an adjacent duct.
Besides, the side surfaces of each duct preferably are inclined outwards from the duct so as to provide a clearance for detaching the rib from the duct. The same applies to the ridges, which thus should have a width that decreases towards their top.
Several different designs of the bottom of the duct are conceivable within the scope of the invention. For example, the bottom of the duct can be cup-shaped between each pair of ridges, but it may alternatively be substantially flat. The bottom of the duct may also exhibit one or more grooves having a width that gradually decreases downwards.